This invention relates to the Universal Serial Bus (USB). USB is a peripheral bus standard developed by PC and telecom industry leaders that bring plug and play of computer peripherals outside the box, eliminating the need to install cards into dedicated computer slots and reconfigure the system. Personal computers equipped with USB allow computer peripherals to be automatically configured as soon as they are physically attachedxe2x80x94without the need to reboot or run setup. USB also allows multiple devicesxe2x80x94up to 127xe2x80x94to run simultaneously on a computer, with peripherals such as monitors and keyboards acting as additional plug-in sites, or hubs.
The cable length is critical in maintaining the signal integrity and the protocol timing. Excessive cabling can cause a USB device not to function correctly or not be recognized by the host system. Device manufacturers are given the freedom to save cost by not building in an expensive overkill. Therefore, by just adding a passive extension cable the signal can be delayed or distorted to an amount that would cause the problem described.
It is the object of the invention to allow a USB device to increase its distance from the host system well beyond the USB specification for cable length while staying within the USB specifications for signal timing.
The invention acts as a repeater. That is, it accepts the signal from one direction via a transceiver, then repeats the same signal out the other direction via another transceiver. The invention also complies with all USB protocol which includes sensing of a high-speed or low-speed device, going into the suspend mode, and detecting an end of packet.